class_docstr: Add a random flipping layer as pre-processing.
code: def _apply_transformation(self, image):
      assert self._rand_flip is not None, "Flip is unset -- Error!"
      for axis_number, do_flip in enumerate(self._rand_flip):
          if axis_number in self._flip_axes and do_flip:
              image = np.flip(image, axis=axis_number)
      return image
  
file_path: NiftyNet/niftynet/layer/rand_flip.py
imports: from __future__ import absolute_import, print_function
  import warnings
  import numpy
  from niftynet.layer.base_layer import RandomisedLayer
label_desc: Use image node_id 3 for calling the RandomFlipLayer obj's underlying member method code with example usage: obj._apply_transformation(image) and returns: image